MORPHOLOGY AND EVOLUTION
A line drawn between the anterior extremities of the ischial tuberosities passes in front of the vulva in the Chimpanzee, but it runs between the vulva and anus in Man.
Sternum,—The Anthropoid Apes agree with Man and differ from the Monkeys in the possession of a wide sternum, hence the name latisternal which is applied to them. The individual sternebrse of which it is composed may be distinguishable. The xiphisternurn is well marked; in the Gibbons it is very large.
The ribs are usually thirteen in number in the Chimpanzee, Gorilla and Gibbons, and twelve in the Orang. Their curvatures give the Apes an ample thorax, which is widest transversely; in the Monkeys the long diameter of the thorax is antero-posterior (ventro-dorsal).
BONES OF THE PECTORAL GIRDLE AND UPPER
Clavicles.—In the Gibbons the clavicles are long, and Owen (122) pointed out that they equal the length of the first eleven dorsal vertebrae. It describes an upward convexity from the sternal to the acromial end, which is flat, triangular and has a large conoid tubercle. In the Orang the clavicle is not so curved as in Man, and the distal end is not so expanded. In the Chimpanzee the clavicle is shorter than in the Gibbon and Orang; the shaft is not so curved, but the flexure at the acromial end is more pronounced; the acromial end is 'less expanded, and the conoid tubercle is large. In the Gorilla the clavicle is thick, and the shaft is nearly